Ketoprofen is a non-biodegradable drug and is not removed by conventional treatments. The need to remove pharmaceutical compounds from water and wastewater has aroused considerable interest in advanced oxidation processes (AOP), whose effectiveness depends on the generation of reactive free radicals capable of oxidizing and decomposing numerous compounds. Heterogeneous photocatalysis is an efficient method if an active semiconductor is used. In this work, the photodegradation reaction of ketoprofen promoted by TiO₂ was studied, analyzing the kinetics obtained by changing variables such as temperature, initial concentration, and quantity of photocatalyst. It was determined that the mechanism is of the Langmuir–Hinshelwood type and that the system is operating in the kinetic regime, while tests at different temperatures have shown that the adsorption of ketoprofen and byproducts are both exothermic. Experimental data were interpreted with reliable models that allow to retrieve quantitatively the kinetic and thermodynamic parameters.